Microsoft says Windows September updates break SMBv1 shares
​Microsoft has confirmed that the September 2025 Windows security updates are causing connection issues to Server Message Block (SMB) v1 shares. The list of platforms affected by this known issue is quite extensive, as it includes both client (Windows 11 24H2/23H2/22H2 and Windows 10 22H2/21H2) and server (Windows Server 2025 and Windows Server 2022) platforms. In a service alert seen by BleepingComputer, Microsoft said this known issue affects those connecting to SMBv1 shares over the NetBIOS